The study of perfusion processes in the body volume of a patient is necessary for the diagnosis of cardiovascular diseases. Such perfusion studies typically involve the injection of a bolus of a contrast agent via a catheter or intravenously and the generation of a sequence of X-ray projections that show the spreading of said bolus in the vessel system and the surrounding tissue. In complex vessel trees like the cerebral vessel tree, it may however be difficult to judge the observed process based on two-dimensional projections acquired in the angio-suite. This is especially true for brain perfusion, where three-dimensional tomographic images of excellent contrast resolution are required for a careful diagnosis.